1. Field of the Invention
The present invention relates to a cathode ray tube (CRT) for use in a terminal display for a computer, a TV set, etc., and more particularly to a nonglare film and a method of forming a nonglare film on a display surface of a display.
2. Description of the Related Art
In recent years, there has been an increased need to prevent the glare due to the reflection of external light on a display surface of a terminal display for a computer, a TV set, etc. To meet this need, various glare-proof means have been used with CRTs. For example, a panel formed with a metal multi-layer antireflection film has been attached to the front surface of a CRT. Another means employs a rough surface that has been formed by chemical etching directly onto the front panel of a CRT in order to scatter external light. Yet another utilizes a coating film formed on a surface of the front panel to exhibit a glare-proof effect. These means are found, for example, in Japanese Patent Laid-open Publication Nos. 60-109134, 60-129778, 60-14685, and 63-80451, and U.S. Pat. No. 4,563,612. In particular, the ""612 patent discloses a cathode ray tube comprising an antistatic, glare-reducing coating having a silicate material and a metallic compound.
However, the above-mentioned related art glare-proof means have the following drawbacks. As for the nonglare means the panel formed with the metal multi-layer antireflection film attached to the front surface of a CRT, the cost is greatly increased, and therefore such a CRT is not suitable for general users. As for the glare-proof means using a CRT with a rough surface directly formed on the front panel itself, the cost can be reduced, but a problem remains with resolution. Further, in the nonglare means utilizing a coating film formed on the surface of the front, there is a possibility that the quality of a reproduced image will be lowered when applying the glare-proof means to a high-definition type CRT, such as a graphic display. That is, enhancement of a glare-proof effect causes an increase in scattered light. As a result, the surface of the front panel looks whitish in bright places, consequently reducing the sharpness of the reproduced image.
Moreover, there is a further need to reduce the accumulation of dust on the CRT front panel. A known technique is to form an antistatic film on the surface of the front panel in order to prevent deposition of dust on the surface of the front panel (for example, Japanese Patent Laid-open Publication Nos. 61-16452, 1-251545, 1-276534, and U.S. Pat. No. 4,563,612).
Accordingly, there is a demand for a high definition type CRT capable of exhibiting an antistatic effect as well as the above-mentioned nonglare effect.
It is the primary object of the present invention to provide a cathode ray tube which can exhibit a nonglare effect and antistatic effect without lowering the quality of a reproduced image.
In accordance with the present invention, there is provided a cathode ray tube comprising a front panel coated with a nonglare film having a multi-layered structure. The multi-layered structure comprises at least a visible light absorbing layer containing a black dye, and an antistatic layer containing an inorganic metal compound as a conductive agent.
In a preferred embodiment, the cathode ray tube includes a visible light absorbing layer formed between the front panel and the antistatic layer.
Further, the nonglare film may be formed by using a water absorbing solvent selected from the group consisting of ethylene glycol, glycerol, diethylene glycol, propylene glycol, triethylene glycol, and hexylene glycol.
In accordance with the another aspect of the present invention, there is provided a method of manufacturing a cathode ray tube having a front panel coated with a nonglare film comprising: cleaning the front panel, heating the front panel for drying, forming a visible light-absorbing layer on the front panel by spraying a first ethyl silicate solution which contains 0.1-0.5 wt % black dye and 1-10 wt % SiO2, forming an antistatic layer on the front panel by spraying a second ethylsilicate solution which contains 40-60 wt % inorganic metal as a conductive agent in a solid content and 1-10 wt % SiO2, and baking the front panel to harden the nonglare film completely.